Can not show data from the script

I use the below command in oracle sql developer , it works fine to output data

SQL> SELECT table1.documentid  FROM table1

documentid
==========
001
002
003

While when use the below script

 SELECT table1.documentid  FROM table1
 join table2 
 on table2.id=table1.documentid ;

the output is "no rows select"

I am wonder why no data will be output , what will be the possible reason of my error ?

really thanks for help